This invention relates to optical packaging assemblies and methods of making the same.
Optical devices typically are packaged in hermetically sealed or plastic molded packages to prevent environmental degradation that otherwise might be caused by, for example, humidity, contaminants, and electrically charged species. Hermetic sealing typically involves mounting an optical device within a metal or ceramic package and enclosing the optical device within the package by soldering, welding, or brazing a cover or lid to the package. The package may include a hermetically sealed electric feedthrough assembly and a hermetically sealed window that allow electrical and optical communication with the enclosed optical device.
Some optical device packages may include hermetically sealed optical fiber feedthroughs, enabling optical fiber communication with the optical devices. In some approaches an optical fiber is fed through a hole in one of the metal walls of an optical device package. Excess solder is applied in a molten state outside the hole to form a solder body surrounding and adhering to the optical fiber. During cooling the molten solder shrinks and the free surface of the solder body also shrinks under the influence of surface tension. The solder is drawn towards the hole and onto and around the glass fiber, thus hermetically sealing in the fiber. In another approach, at least one optical fiber and at least one solder preform is placed between the sealing surface of a package lid and the sealing surface of a package housing; the assembly then is sealed by applying pressure and heat so as to press the fiber (or fibers) into the solder (see U.S. Pat. No. 6,216,939). Commonly, an array of optical fibers is needed, rather than a single fiber. In general, package manufacturing complexity and cost increases with the number of fibers because each optical fiber requires a respective hermetical feedthrough.
The invention features optical packaging schemes that enable the tasks of hermetically sealing optical devices against environmental degradation and aligning the optical devices with optical fibers to be separated. In this way, the invention satisfies the need to protect optical devices against environmental damage while avoiding the costs and complexity associated with hermetically sealed optical fiber arrangements.
In one aspect of the invention, an optical packaging assembly includes a package housing, a hermetically sealed optical device housing, and an optical fiber alignment assembly. The package housing includes an optical fiber feedthrough and a package electric feedthrough. One or more optical fibers extend through the optical fiber feedthrough. The hermetically sealed optical device housing is mounted within the package housing and includes an optical window and a device electric feedthrough that is electrically connected to the electric feedthrough of the package housing. At least one optical device is mounted within the hermetically sealed optical device housing in optical alignment with respect to the optical window. The optical fiber alignment assembly is mounted within the package housing and holds end portions of the one or more optical fibers in alignment for optical communication through the window of the hermetically sealed optical device housing.
In another aspect, the invention features a method of making the above-described optical packaging assembly.